The difference between full displacement and semi-displacement hulls on a trawler is primarily in their design and performance characteristics:
- Full Displacement Hulls:
- These hulls are designed to move through the water by displacing it.
- They are typically more rounded and bulkier, making them very efficient and seaworthy in rough waters.
- Full displacement hulls are limited to slower speeds, known as “hull speed,” which is determined by the length of the waterline.
- They are most economical at these lower speeds and often have lower horsepower engines, resulting in lower fuel and maintenance costs1.
- Semi-Displacement Hulls:
- Semi-displacement hulls combine features of both displacement and planning hulls.
- At low speeds, they displace water like a full displacement hull, but they can generate lift and semi-planning as speed increases.
- This design allows for greater speed than full displacement hulls while maintaining stability and seaworthiness.
- They often have more horsepower than full displacement hulls and can operate faster, but this comes with higher fuel consumption2.
In essence, a full-displacement hull is suitable if you priorities economy and are comfortable with lower speeds. If you need a balance between speed and seaworthiness, a semi-displacement hull might be better. Each type has its advantages for different boating needs and preferences.